1. Field of the Invention
The present invention generally relates to an audio signal processing apparatus for adding a harmony signal to an audio signal. The present invention also relates to an audio signal processing apparatus for generating, based on a first audio signal, a second audio signal of which pitch is controlled by the pitch of the first audio signal. Further, the present invention relates to an audio signal processing apparatus for imparting an effect to an audio signal. Still further, the present invention relates to an audio signal processing apparatus for processing two or more audio signals such that two or more sound images are localized at random positions when two or more audio signals are sounded.
2. Description of Related Art
Japanese Published Unexamined Patent Application No. Hei 4-42297 discloses a technology by which the pitch of an input voice signal is detected in real time and a harmony voice signal is mixed to the voice of the singer. Recently, this technology is commercially available in a plug-in board of a tone generator. In this plug-in board, the pitch of an inputted voice signal is shifted to provide a harmony voice signal, which is then mixed with an original voice signal, and a resultant mixed signal is outputted from a loudspeaker. However, because the original voice and the harmony voice have similar voice quality, the harmony voice becomes blurred. In addition, because performance expressions using the pitch-shifted harmony voice are limited in variety, monotonous performances sometimes result.
Japanese Published Examined Patent Application No. Hei 4-51838 discloses an audio signal processing apparatus for detecting the pitch of a singer""s voice, forming note data from the detected pitch, sequentially storing the formed note data, and sequentially reading the stored note data for music performance. The disclosed apparatus allows the singer to merely sing to generate corresponding music tones without playing a keyboard. However, the actual pitch of the detected input voice signal is rounded to a discrete pitch that corresponds to note names of music. This causes stepwise change in pitch. Therefore, such an apparatus is suitable for playing keyboard musical instruments in which tones are played by discrete pitches. As for singing, however, a voice pitch is sometimes varied continuously. In this case, a corresponding tone of which pitch is continuously varied must be generated according to the pitch of the continuously changing voice. Modifying the note data by editing may partially impart a continuous variation to the pitch of the stepwise music tone. However, the processing required is time-consuming and burdensome. On the other hand, Japanese Published Unexamined Patent Application No. Hei 4-242290 discloses a method of generating only note information when converting the pitch of an input voice into performance information, or generating both note information and pitch bend information. However, the conventional method is not intended to appropriately switch between the two modes of converting the pitch into performance information as required. The conventional method does not consider the processing to be executed when the voice pitch continuously varies beyond the pitch bend range.
A so-called delay effect is known such that imparting of an effect to a music tone signal is started after passing of a preset delay time from starting the generation of the tone signal. Such a delay effect includes delay vibrato and delay tremolo. For example, the delay effect is imparted as follows to a music tone signal continuously sounded. FIG. 5B illustrates how the delay effect is imparted conventionally. The effect to be imparted in FIG. 5B is delay vibrato for example. Referring to FIG. 5B, to continuously vary a pitch, plural tone signals (1) through (4) are successively and continuously sounded. When the top tone signal (1) enters a note-off state, the next tone signal (2) enters a note-on state. This holds true for the subsequent tone signals (2) through (4). When the delay vibrato is imparted to these continuous tone signals (1) through (4), the imparting of the effect starts after a predetermined time from the note-on event and stops at the end of the music tone signal (1). This holds true for the subsequent continuous tone signals. Consequently, the imparted effect becomes intermittent on the continuous tone signals (1) through (4) in spite of the intention that the delay effect should provide substantially one continuous tone in performance, thereby causing a feeling of disagreeableness.
Random panning has been conventionally practiced as a sort of acoustic effect. In the random panning, a tone signal is localized in a random fashion. For example, in the random panning, a tone signal played by a user is heard as if traveling from random positions, somewhere on the right side and then somewhere on the left side relative to the user. However, an attempt to localize the sound images of two or more tone signals in a random fashion may incidentally results in the localization of different tone signals at the same position. If this happens, the tone signals are clustered at one point, suddenly making the sound field width narrow. Especially, when two or more sound images are localized at the center point, the sound field is made extremely narrow.
It is therefore a first object of the present invention to provide an audio signal processing apparatus for generating a highly distinct harmony voice over an original voice. This processing apparatus is also intended to impart various effects to the harmony voice.
It is a second object of the present invention to provide an audio signal processing apparatus that, when generating a second audio signal of which pitch is controlled based on the pitch of a first audio signal, allows a user to select between a performance in which the pitch varies stepwise in registration with a pitch name or note of the first audio signal and another performance in which the pitch continuously varies following the pitch of the first audio signal.
It is a third object of the present invention to provide an audio signal processing apparatus that generates an audio signal of which pitch continuously varies following a continuously varying pitch of another audio signal, and that makes smooth the pitch change of the generated audio signal.
It is a fourth object of the present invention to provide an audio signal processing apparatus for continuously imparting a time-varying effect such as a delay effect to two or more continuous audio signals.
It is a fifth object of the present invention to provide an audio signal processing apparatus for imparting a stable random panning effect to two or more harmony audio signals.
In a first aspect of the invention, an audio processing apparatus is constructed for generating an auxiliary audio signal based on an original audio signal and mixing the auxiliary audio signal to the original audio signal. In the inventive apparatus, a control section designates a pitch of the auxiliary audio signal. A processing section processes the original audio signal under control of the control section to generate the auxiliary audio signal having the designated pitch, and applies a first effect to the generated auxiliary audio signal. An effector section applies a second effect different from the first effect to the original audio signal. An output section outputs the original audio signal applied with the second effect concurrently with the auxiliary audio signal applied with the first effect. Preferably, the control section controls the processing section to alter the first effect dependently on a difference between a pitch of the original audio signal and the designated pitch of the auxiliary audio signal.
Further, the inventive audio processing apparatus is constructed for generating an auxiliary audio signal based on an original audio signal. In the inventive apparatus, a detecting section detects an original pitch of the original audio signal. A processing section carries out a pitch conversion of the original audio signal based on the detected original pitch to generate the auxiliary audio signal having a converted pitch, and applies an effect to the generated auxiliary audio signal. A control section controls the processing section to alter the effect applied to the auxiliary audio signal dependently on a difference between the original pitch of the original audio signal and the converted pitch of the auxiliary audio signal.
In a second aspect of the invention, an audio processing apparatus is constructed for generating a synthetic audio signal in response to an original audio signal. In the inventive apparatus, a detecting section sequentially detects a pitch of the original audio signal. A generating section generates the synthetic audio signal having a pitch varying in response to that of the original audio signal. A control section operates in a first mode for quantizing the detected pitch of the original audio signal into a sequence of notes to control the generating section such that the pitch of the synthetic audio signal varies stepwise in matching with the sequence of the notes, and operates in a second mode for controlling the generating section according to the detected pitch of the original audio signal such that the pitch of the synthetic audio signal continuously varies to follow that of the original audio signal. A switch section switches the control section between the first mode and the second mode. Preferably, the switch section can switch the control section while the generating section is generating the synthetic audio signal.
Further, the inventive audio processing apparatus is constructed for generating a synthetic audio signal in response to an original audio signal. In the inventive apparatus, a detecting section detects a pitch of the original audio signal. Another detecting section detects a volume of the original audio signal. A generating section generates the synthetic audio signal. A control section controls the generating section to vary a pitch of the synthetic audio signal according to the detected pitch of the original audio signal. Another control section controls the generating section to vary a volume of the synthetic audio signal according to the detected volume of the original audio signal.
In a third aspect of the invention, an audio processing apparatus is constructed for generating a synthetic audio signal in response to an original audio signal. In the inventive apparatus, a detecting section detects a varying pitch of the original audio signal. A generating section generates the synthetic audio signal. A control section controls the generating section to vary a pitch of the synthetic audio signal according to the detected varying pitch of the original audio signal. The control section determines a first note from the detected varying pitch of the original audio signal for controlling the generating section to generate the first note of the synthetic audio signal while bending a pitch of the synthetic audio signal around the first note in response to a deviation of the detected varying pitch from the first note. Then, the control section determines a second note from the detected varying pitch when the deviation thereof from the first note exceeds a predetermined value for controlling the generating section to stop the first note and to generate the second note of the synthetic audio signal. Preferably, the generating section generates the first note and the second note which has an amplitude envelope substantially the same as that of the first note.
In a fourth aspect of the invention, an audio processing apparatus is constructed for applying an effect to an audio signal. In the inventive apparatus, a generating section is controlled to generate the audio signal for creating either of a continuous sequence of music notes and a discrete sequence of music notes. An effector section is triggered in response to an occurrence of each music note for applying a time-varying effect to each music note of the generated audio signal. A control section operates when the generating section generates the continuous sequence of the music notes including a first music note and subsequent music notes for controlling the effector section to maintain the time-varying effect once applied to the first music note even after the first music note ceases so that the time-varying effect is continuously applied to the subsequent music notes while preventing further time-varying effects from being triggered in response to the subsequent music notes. Preferably, the effector section starts application of the time-varying effect to the music note with a predetermined delay of time after the generating section starts generation of the music note.
In a fifth aspect of the invention, an audio processing apparatus is constructed for locating a plurality of audio signals to a plurality of regions. In the inventive apparatus, an input section provides the plurality of the audio signals concurrently with each other. An output section mixes the plurality of the audio signals with each other while locating the plurality of the audio signals to the plurality of the regions. A control section controls the output section to randomize the locating of the audio signals. The control section comprises a determination sub section that randomly assigns one region to one of the audio signals, a memory sub section that memorizes said one region assigned to said one audio signal, and another determination subsection that randomly assigns another of the regions except for said memorized region to another of the audio signals to thereby avoid duplicate assignment of the same region to different ones of the audio signals while ensuring randomization of the locating of the audio signals.